This paper studies a landfill where there are three faults running through. As serious pollution has occurred to the geological environment, the landfill is to be closed up and renovated. The paper aims to explore the...This paper studies a landfill where there are three faults running through. As serious pollution has occurred to the geological environment, the landfill is to be closed up and renovated. The paper aims to explore the role of fracture structure in leachate pollution at the landfill. The research was carried out in several stages. First, mathematical models of the pre-renovation landfill with three faults running through and the landfill after renovation were established. And then, the boundary conditions and parameters of the two mathematical models were determined. The groundwater level of the landfills was simulated in order to modify the two mathematical models. As a result, a feasible mathematical model was achieved. Based on this model, a comparison was made of the COD concentration variations in the inside leachate and outside leachate between the two landfills. Accordingly, the impacts of the fracture structure on the pollution of leachate at the landfills could be identified. The study results show that while faults contribute to the migration of ieachate, they also serve as a confluence of leachate, thus further deteriorating the environment. The COD concentrations of the inside leachate and the outside leachate of the pre-renovation landfill are respectively 800 mg/L and 220 mg/L higher than those of the post-renovation landfill. Therefore, measures must be taken to handle the ieachate seepage in areas where there are faults as well as the neighboring areas so as to get the environmental pollution under control.展开更多
Several structure sets (faults and folds) are characterized by their self-similarity properties. Herein, we discuss the degrees of complexity of fractures by introducing the box-counting fractal dimension of faults ...Several structure sets (faults and folds) are characterized by their self-similarity properties. Herein, we discuss the degrees of complexity of fractures by introducing the box-counting fractal dimension of faults as a key criterion to be used in comprehensive fuzzy analysis model for evaluation of the complexity of structures. Totally, eight criteria including density, intensity, length of faults, types and box-counting fractal dimension of faults, the intersection angle between faults and coal beds, gradient coefficients, dip angles of the coal beds, and variation coefficients of dip angles of the coal seams, were used for the evaluation purpose. The grey fuzzy comprehensive assessment model was used to rank the relative importance of these criteria. Scores indicating the complexity of structure were calculated on the base of criteria values and their weights for each sub-area of the study area in the Pansan (潘三) coal mine district in the southern Anhui (安徽) Province, China. The result on the calculated complexity of structure is useful for mining planning in the study area.展开更多
According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific probl...According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific problems whichmust be studied i, the elucidation emphasizes that the core of this project is to study the conditions and processesof the generation of strong earthquakes. The paper first outlines the origin and development of the'strong-bodyearthquake-generating model' proposed by the author in the 1980;and then proves the reasonableness of themodel from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. Bystudying the tomographic image for the northern part of North China, it can be seen that the sources of strongearthquakes are all distributed in high-velocity bodies,or in the contact zone between high-velocity and lowvelocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical modelsof hard and soft inclusions that the existence of a hard inclusion is an imPOrtant condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability,sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmentalstiffness.展开更多
With annually increased coal mining depth,gas extraction becomes more and more problematic.The gas extraction efect depends on coal seam permeability,which,in turn,is afected by many factors,including loading and unlo...With annually increased coal mining depth,gas extraction becomes more and more problematic.The gas extraction efect depends on coal seam permeability,which,in turn,is afected by many factors,including loading and unloading stresses and strains in the coal seam.Stresses induce internal cracks,resulting in cleats and gas emission channels,the coal seam permeability permanently changes accordingly.To clarify the stress-induced efects on coal seam permeability,this survey summarized the available approaches used to link the stress path and seepage law in the coal body seepage law,which can be classifed into two design methods:single load variation and combined feld mining method.The characterization methods used to observe the surface of coal samples and three-dimensional reconstruction include electron microscopy,CT scanning,and Nuclear Magnetic Resonance(NMR).According to the stress paths designed by the above two approaches,the seepage laws and similarities of three kinds of coal samples with the fractured structure were summarized in this paper.The following directions are recommended to study the seepage law of coal bodies with three kinds of fractured structures under stress.Firstly,the stress path of the experimental coal body should be designed by the combined feld mining method.The stressed environment of a deep coal seam is complicated,and the axial and confning pressures change simultaneously.Therefore,one cannot fully refect the real situation on-site by studying permeability evolution alone.Secondly,during the coal seam mining,the stressed state changes from time to time,and the development of coal seam fractures is afected by mining.When studying the stress efect on seepage of coal samples,the fractured structure of coal samples should be considered.Finally,the available structural characterization methods of coal samples can be combined with the 3D printing technology,which would produce artifcial samples with the fractured structure characteristics of natural coal.展开更多
The predominant presence of weak interlayers primarily composed of mudstone renders them highly susceptible to a reduction in bearing capacity due to the water-rock weakening effect,significantly impacting the safety ...The predominant presence of weak interlayers primarily composed of mudstone renders them highly susceptible to a reduction in bearing capacity due to the water-rock weakening effect,significantly impacting the safety of open-pit mining operations.This study focuses on the weak mudstone layers within open-pit mine slopes.The mineral composition of mudstone and the microstructure evolution characteristics before and after water wetting were analyzed by X-ray diffraction(XRD)and scanning electron microscope(SEM).The meso-structure and parameter variation characteristics of mudstone interior space after water-rock interaction were quantified by computed tomography scanning test,and the damage variable characterization method was proposed.Additionally,according to the uniaxial compression test,the degradation characteristics of the macroscopic mechanical behavior of mudstone under different water wetting time were explored,and the elastic modulus and strength attenuation model of mudstone based on mesoscopic damage were established.Finally,building upon the macro-meso structural response characteristics of mudstone,an exploration of the failure characteristics and deterioration mechanism under the influence of water-rock interactions was undertaken.The results show that the water-rock interaction makes the internal defects of mudstone gradually develop and form a fracture network structure,which eventually leads to the deterioration of its macroscopic mechanical properties.The porosity,fractal dimension and damage characteristics of mudstone show an exponential trend with the increase of water wetting time.Moreover,the deterioration mechanism of mudstone after water wetting are postulated to encompass factors such as the hydrophilicity of mineral molecular structures,hydration stress and expansion effects on clay particles,as well as the spatial distribution of microcracks and the phenomenon of fracture adsorption.The outcomes of this research endeavor aim to provide certain reference value for further understanding the water-rock interaction and stability control of mudstone slope.展开更多
The southern Junggar Basin has enormous hydrocarbon mainly from the Jurassic and Permian source rocks,which indicated the importance of exploration of the deeply buried Jurassic reservoirs,therefore,the study of the d...The southern Junggar Basin has enormous hydrocarbon mainly from the Jurassic and Permian source rocks,which indicated the importance of exploration of the deeply buried Jurassic reservoirs,therefore,the study of the deeply buried Upper Jurassic Qigu Formation(J_(3)q)reservoirs in Well DS-1 in the Dushanzi anticline was carried out through microscopic observation and measurement,nuclear magnetic resonance(NMR),scanning electron microscopy(SEM)and high pressure mercury injection.Results showed that the main reservoir storage spaces in the deeply buried Upper Jurassic Qigu Formation reservoirs were fractures and dissolved pores.The J_(3)q reservoirs with low porosity and permeability values of 0e12%and(0e5)×10^(-3)mm^(2) respectively,were generally tight.According to the mercury injection data,heterogeneity existed in the deeply buried Qigu Formation reservoirs with inhomogeneous pores and changeable sizes of pores throats.Pores and pore throats in the silt-fine sandstones of the lower Qigu Formation(J_(3)q^(1))were more big and wide respectively than that in the argillaceous siltstones of the upper Qigu Formation(J_(3)q^(3)).Reservoirs in J_(3)q^(1) had more mobile fluid and better conductivities than reservoirs in J_(3)q^(3).The strong compaction and multistage diagenesis resulted in the tight J_(3)q reservoirs.Anhydrite and quartz cementation,and various authigenetic minerals(e.g.hematite,kaolinite,illite/smectite formation,illite,chlorite and zeolite)filled in the pores.The homogenization temperature of brine inclusions(63.1e161.7℃)in quartz overgrowth indicated the quartz had grown since the late Eocene.Due to the Tian Shan reactivity in the Late Cenozoic,the structure fractures were developed and promoted dissolution by oil and formation water in the reservoirs of J3q1.展开更多
基金the Natural Science Foundation of Chongqing (Grant No.cstc.2004BB7059);the Foundation of Municipal Committee of Chongqing City(No.200511).
文摘This paper studies a landfill where there are three faults running through. As serious pollution has occurred to the geological environment, the landfill is to be closed up and renovated. The paper aims to explore the role of fracture structure in leachate pollution at the landfill. The research was carried out in several stages. First, mathematical models of the pre-renovation landfill with three faults running through and the landfill after renovation were established. And then, the boundary conditions and parameters of the two mathematical models were determined. The groundwater level of the landfills was simulated in order to modify the two mathematical models. As a result, a feasible mathematical model was achieved. Based on this model, a comparison was made of the COD concentration variations in the inside leachate and outside leachate between the two landfills. Accordingly, the impacts of the fracture structure on the pollution of leachate at the landfills could be identified. The study results show that while faults contribute to the migration of ieachate, they also serve as a confluence of leachate, thus further deteriorating the environment. The COD concentrations of the inside leachate and the outside leachate of the pre-renovation landfill are respectively 800 mg/L and 220 mg/L higher than those of the post-renovation landfill. Therefore, measures must be taken to handle the ieachate seepage in areas where there are faults as well as the neighboring areas so as to get the environmental pollution under control.
基金supported by the National Basic Research Program of China (Nos. 2006CB4035008, 2002CB412600)the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences
文摘Several structure sets (faults and folds) are characterized by their self-similarity properties. Herein, we discuss the degrees of complexity of fractures by introducing the box-counting fractal dimension of faults as a key criterion to be used in comprehensive fuzzy analysis model for evaluation of the complexity of structures. Totally, eight criteria including density, intensity, length of faults, types and box-counting fractal dimension of faults, the intersection angle between faults and coal beds, gradient coefficients, dip angles of the coal beds, and variation coefficients of dip angles of the coal seams, were used for the evaluation purpose. The grey fuzzy comprehensive assessment model was used to rank the relative importance of these criteria. Scores indicating the complexity of structure were calculated on the base of criteria values and their weights for each sub-area of the study area in the Pansan (潘三) coal mine district in the southern Anhui (安徽) Province, China. The result on the calculated complexity of structure is useful for mining planning in the study area.
文摘According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific problems whichmust be studied i, the elucidation emphasizes that the core of this project is to study the conditions and processesof the generation of strong earthquakes. The paper first outlines the origin and development of the'strong-bodyearthquake-generating model' proposed by the author in the 1980;and then proves the reasonableness of themodel from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. Bystudying the tomographic image for the northern part of North China, it can be seen that the sources of strongearthquakes are all distributed in high-velocity bodies,or in the contact zone between high-velocity and lowvelocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical modelsof hard and soft inclusions that the existence of a hard inclusion is an imPOrtant condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability,sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmentalstiffness.
基金supported by the National Natural Science Foundation of China(52174129,52104155,51704274)Independent Research Project of State Key Laboratory of Coal Resources and Safe Mining,CUMT(SKLCRSM22X006)Jiangsu Province Scientifc Research and Practice Innovation Project(KYCX21_2390).
文摘With annually increased coal mining depth,gas extraction becomes more and more problematic.The gas extraction efect depends on coal seam permeability,which,in turn,is afected by many factors,including loading and unloading stresses and strains in the coal seam.Stresses induce internal cracks,resulting in cleats and gas emission channels,the coal seam permeability permanently changes accordingly.To clarify the stress-induced efects on coal seam permeability,this survey summarized the available approaches used to link the stress path and seepage law in the coal body seepage law,which can be classifed into two design methods:single load variation and combined feld mining method.The characterization methods used to observe the surface of coal samples and three-dimensional reconstruction include electron microscopy,CT scanning,and Nuclear Magnetic Resonance(NMR).According to the stress paths designed by the above two approaches,the seepage laws and similarities of three kinds of coal samples with the fractured structure were summarized in this paper.The following directions are recommended to study the seepage law of coal bodies with three kinds of fractured structures under stress.Firstly,the stress path of the experimental coal body should be designed by the combined feld mining method.The stressed environment of a deep coal seam is complicated,and the axial and confning pressures change simultaneously.Therefore,one cannot fully refect the real situation on-site by studying permeability evolution alone.Secondly,during the coal seam mining,the stressed state changes from time to time,and the development of coal seam fractures is afected by mining.When studying the stress efect on seepage of coal samples,the fractured structure of coal samples should be considered.Finally,the available structural characterization methods of coal samples can be combined with the 3D printing technology,which would produce artifcial samples with the fractured structure characteristics of natural coal.
基金We gratefully acknowledge the financial support by the National Key Research and Development Program of China(2022YFC2904100)the State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Beijing(SKLCRSM20KFA11).
文摘The predominant presence of weak interlayers primarily composed of mudstone renders them highly susceptible to a reduction in bearing capacity due to the water-rock weakening effect,significantly impacting the safety of open-pit mining operations.This study focuses on the weak mudstone layers within open-pit mine slopes.The mineral composition of mudstone and the microstructure evolution characteristics before and after water wetting were analyzed by X-ray diffraction(XRD)and scanning electron microscope(SEM).The meso-structure and parameter variation characteristics of mudstone interior space after water-rock interaction were quantified by computed tomography scanning test,and the damage variable characterization method was proposed.Additionally,according to the uniaxial compression test,the degradation characteristics of the macroscopic mechanical behavior of mudstone under different water wetting time were explored,and the elastic modulus and strength attenuation model of mudstone based on mesoscopic damage were established.Finally,building upon the macro-meso structural response characteristics of mudstone,an exploration of the failure characteristics and deterioration mechanism under the influence of water-rock interactions was undertaken.The results show that the water-rock interaction makes the internal defects of mudstone gradually develop and form a fracture network structure,which eventually leads to the deterioration of its macroscopic mechanical properties.The porosity,fractal dimension and damage characteristics of mudstone show an exponential trend with the increase of water wetting time.Moreover,the deterioration mechanism of mudstone after water wetting are postulated to encompass factors such as the hydrophilicity of mineral molecular structures,hydration stress and expansion effects on clay particles,as well as the spatial distribution of microcracks and the phenomenon of fracture adsorption.The outcomes of this research endeavor aim to provide certain reference value for further understanding the water-rock interaction and stability control of mudstone slope.
基金The work was supported by the National Science and Technology Major Project of China(No.2017ZX05008-001,No.2016ZX05003-002)the 13th Five-year Program of PetroChina(2016B-0502).
文摘The southern Junggar Basin has enormous hydrocarbon mainly from the Jurassic and Permian source rocks,which indicated the importance of exploration of the deeply buried Jurassic reservoirs,therefore,the study of the deeply buried Upper Jurassic Qigu Formation(J_(3)q)reservoirs in Well DS-1 in the Dushanzi anticline was carried out through microscopic observation and measurement,nuclear magnetic resonance(NMR),scanning electron microscopy(SEM)and high pressure mercury injection.Results showed that the main reservoir storage spaces in the deeply buried Upper Jurassic Qigu Formation reservoirs were fractures and dissolved pores.The J_(3)q reservoirs with low porosity and permeability values of 0e12%and(0e5)×10^(-3)mm^(2) respectively,were generally tight.According to the mercury injection data,heterogeneity existed in the deeply buried Qigu Formation reservoirs with inhomogeneous pores and changeable sizes of pores throats.Pores and pore throats in the silt-fine sandstones of the lower Qigu Formation(J_(3)q^(1))were more big and wide respectively than that in the argillaceous siltstones of the upper Qigu Formation(J_(3)q^(3)).Reservoirs in J_(3)q^(1) had more mobile fluid and better conductivities than reservoirs in J_(3)q^(3).The strong compaction and multistage diagenesis resulted in the tight J_(3)q reservoirs.Anhydrite and quartz cementation,and various authigenetic minerals(e.g.hematite,kaolinite,illite/smectite formation,illite,chlorite and zeolite)filled in the pores.The homogenization temperature of brine inclusions(63.1e161.7℃)in quartz overgrowth indicated the quartz had grown since the late Eocene.Due to the Tian Shan reactivity in the Late Cenozoic,the structure fractures were developed and promoted dissolution by oil and formation water in the reservoirs of J3q1.